Dissertations / Theses on the topic 'Grouping'
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Rundqvist, David. "Grouping Biological Data." Thesis, Linköping University, Department of Computer and Information Science, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6327.
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Today, scientists in various biomedical fields rely on biological data sources in their research. Large amounts of information concerning, for instance, genes, proteins and diseases are publicly available on the internet, and are used daily for acquiring knowledge. Typically, biological data is spread across multiple sources, which has led to heterogeneity and redundancy.
The current thesis suggests grouping as one way of computationally managing biological data. A conceptual model for this purpose is presented, which takes properties specific for biological data into account. The model defines sub-tasks and key issues where multiple solutions are possible, and describes what approaches for these that have been used in earlier work. Further, an implementation of this model is described, as well as test cases which show that the model is indeed useful.
Since the use of ontologies is relatively new in the management of biological data, the main focus of the thesis is on how semantic similarity of ontological annotations can be used for grouping. The results of the test cases show for example that the implementation of the model, using Gene Ontology, is capable of producing groups of data entries with similar molecular functions.
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McMillan, Allison. "Dairy cattle grouping /." Click here to view, 2009. http://digitalcommons.calpoly.edu/dscisp/7.
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Thesis (B.S.)--California Polytechnic State University, 2009.Project advisor: Edwin Jaster. Title from PDF title page; viewed on Jan. 21, 2010. Includes bibliographical references. Also available on microfiche.
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Dawara, Santosh. "Grouping related attributes /." Link to online version, 2004. https://ritdml.rit.edu/dspace/handle/1850/438.
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Gibeault, Kimberly. "The use of ability grouping and flexible grouping within guided reading." Online version, 2008. http://www.uwstout.edu/lib/thesis/2008/2008gibeaultk.pdf.
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Zhao, Zhenyuan. "Dynamical Grouping in Complex Systems." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/498.
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Quantifying the behavior of complex systems arguably presents the common ¡°hard¡±problem across the physical, biological, social, economic sciences. Individual-based or agent-based models have proved useful in a variety of different real world systems: from the physical, biological, medical domains through to social and even financial domains. There are many different models in each of these fields, each with their own particular assumptions, strengths and weaknesses for particular application areas. However, there is a lack of minimal model analysis in which both numerical and analytic results can be obtained, and hence allowing different application domains to be analyzed on a common footing. This thesis focuses on a few simple, yet highly non-trivial, minimal models of a population of interacting objects (so-called agents) featuring internal dynamical grouping. In addition to analyzing these models, I apply them to a number of distinct real world systems. Both the numerical and analytical results suggest that these simple models could be key factors in explaining the overall collective behavior and emergent properties in a wide range of real world complex systems. In particular, I study variants of a particular model (called the EZ model) in order to explain the attrition time in modern conflicts, and the evolution of contagion phenomena in such a dynamically evolving population. I also study and explain the empirical data obtained for online guilds and offline gangs, leading to a team-based model which captures the common quantitative features of the data. I then move on to develop a resource competition model (i.e. the so-called El Farol model) and apply it to the carbon emissions market, mapping the different market factors into model parameters which enable me to explore the potential market behaviors under a variety of scenarios.
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Wildeman, Ralph Edwin. "The art of grouping maintenance." Rotterdam : Rotterdam : De Auteur ; Erasmus University [Host], 1996. http://www.eur.nl/WebDOC/doc/tinbergen/tir19960111120002.ps.
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Zheng, Ling. "Feature grouping-based feature selection." Thesis, Aberystwyth University, 2017. http://hdl.handle.net/2160/41e7b226-d8e1-481f-9c48-4983f64b0a92.
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Feature selection (FS) is a process which aims to select input domain features that are most informative for a given outcome. Unlike other dimensionality reduction techniques, feature selection methods preserve the underlying semantics or meaning of the original data following reduction. Typically, FS can be divided into four categories: filter, wrapper, hybrid-based and embedded approaches. Many strategies have been proposed for this task in an effort to identify more compact and better quality feature subsets. As various advanced techniques have emerged in the development of search mechanisms, it has become increasingly possible for quality feature subsets to be discovered efficiently without resorting to exhaustive search. Harmony search is a music-inspired stochastic search method. This general technique can be used to support FS in conjunction with many available feature subset quality evaluation methods. The structural simplicity of this technique means that it is capable of reducing the overall complexity of the subset search. The naturally stochastic properties of this technique also help to reduce local optima for any resultant feature subset, whilst locating multiple, potential candidates for the final subset. However, it is not sufficiently flexible in adjusting the size of the parametric musician population, which directly affects the performance on feature subset size reduction. This weakness can be alleviated to a certain extent by an iterative refinement extension, but the fundamental issue remains. Stochastic mechanisms have not been explored to their maximum potential by the original work, as it does not employ a parameter of pitch adjustment rate due to its ineffective mapping of concepts. To address the above problems, this thesis proposes a series of extensions. Firstly, a self-adjusting approach is proposed for the task of FS which involves a mechanism to further improve the performance of the existing harmony search-based method. This approach introduces three novel techniques: a restricted feature domain created for each individual musician contributing to the harmony improvisation in order to improve harmony diversity; a harmony memory consolidation which explores the possibility of exchanging/communicating information amongst musicians such that it can dynamically adjust the population of musicians in improvising new harmonies; and a pitch adjustment which exploits feature similarity measures to identify neighbouring features in order to fine-tune the newly discovered harmonies. These novel developments are also supplemented by a further new proposal involving the application to a feature grouping-based approach proposed herein for FS, which works by searching for feature subsets across homogeneous feature groups rather than examining a massive number of possible combinations of features. This approach radically departs from the traditional FS techniques that work by incrementally adding/removing features from a candidate feature subset one feature at a time or randomly selecting feature combinations without considering the relationship(s) between features. As such, information such as inter-feature correlation may be retained and the residual redundancy in the returned feature subset minimised. Two different instantiations of an FS mechanism are derived from such a feature grouping-based framework: one based upon the straightforward ranking of features within the resultant feature grouping; and the other on the simplification for harmony search-based FS. Feature grouping-based FS offers a self-adjusting approach to effectively and efficiently addressing many real-world problems which may have data dimensionality concerns and which requires semantic-preserving in data reduction. This thesis investigate the application of this approach in the area of intrusion detection, which must deal in a timely fashion with huge quantities of data extracted from network traffic or audit trails. This approach empirically demonstrates the efficacy of feature grouping-based FS in action.
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Henderson, Robert. "Swarms: Spatiotemporal grouping across domains." Springer, 2016. http://hdl.handle.net/10150/622353.
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First Online: 21 March 2016. 12 month embargo.This paper presents cross-domain evidence that natural language makes use of (at least) two ways of individuating collective entities that differ in terms of how they cohere. The first kind, which I call swarm reference, picks out higher-order collective entities defined in terms of the spatial and temporal configuration of their constituent individuals. The second, which corresponds to canonical cases of group reference (e.g. committee, team, etc.), makes use of non-spatiotemporal notions. To motivate this distinction, I present systematic differences in how these two types of collective reference behave linguistically, both in the individual and event domains. These differences support two primary results. First, they are used as tests to isolate a new class of collective nouns that denote swarm individuals, both in English, as well as other languages like Romanian. I then consider a crosslinguistically common type of pluractionality, called event-internal in the previous literature (Cusic 1981, Wood 2007), and show that its properties are best explained if the relevant verbs denote swarm events. By reducing event-internal pluractionality to a type of collective reference also available for nouns, this work generates a new strong argument that pluractionality involves the same varieties of plural reference in the event domain that are seen in the individual domain.
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Vieira, Sérgio Filipe Gonçalves. "Object grouping in limited spaces." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/21737.
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Mestrado em Engenharia Eletrónica e TelecomunicaçõesCom a crescente necessidade de transporte de mercadoria como resultado da globalização económica, é importante o melhoramento dos processos e procedimentos das operações logísticas como o carregamento e descarregamento de mercadoria, por forma às corporações aumentarem a sua vantagem competitiva e rentabilidade. Esta dissertação explora e apresenta dois temas relacionados com processos logísticos: Posicionamento de volumes e tecnologias de deteção para monitorização de mercadorias. Uma heurística foi desenvolvida para atribuição e posicionamento 3D de volumes dentro de contentores seguindo uma estratégia de colocação que produz soluções verticalmente estáveis e com um alto grau de compactação. Desenvolveram-se dois protótipos usando tecnologia de deteção capaz de medição de volumes, varrimento por laser e visão estereoscópica por computador, como fundação para um sistema para monitorizar o carregamento e descarregamento de mercadorias. Estes sistemas pretendem providenciar assistência para os operadores logísticos na aplicação de normas e identificação de potenciais problemas. Os resultados obtidos pela heurística são promissores, mostrando que um conjunto de simples regras de posicionamento de caixas consegue obter uma boa percentagem de ocupação de volume do contentor. Ambos os protótipos de deteção apresentaram bons resultados nos testes de laboratório, com o protótipo de visão estereoscópica provando ser o mais preciso e fiável para potencial desenvolvimento em uma aplicação a ser instalada em contentores. Esta dissertação conclui com observações acerca de futuros melhoramentos e desenvolvimentos para o trabalho implementado.
With the ever necessity of cargo transportation as the results of economic globalization, it is important to improve the processes and procedures of logistic operations such as cargo loading and unloading, in order for corporations to increase their competitive advantage and profitability. This dissertation explores and presents two subjects related with logistic processes: Volume placement and sensing technologies for cargo monitoring. A heuristic was developed for 3D volume assignment and placement inside containers following a positioning strategy that produces vertically stable solutions with a high degree of compactness. Two prototypes using sensing technology capable of volume measurement, laser range finding and computer stereo vision, were developed as a foundation for a system for monitoring the loading and unloading of cargo. These systems aim to provide assistance to logistic operators on the application of standards and identification of potential issues. The obtained results on the heuristic are promising, showing that a simple set of rules for placement of boxes can achieve a good occupation percentage of the container’s volume. Both sensing prototypes showed good results on lab tests with the stereo vision prototype proving to be the most accurate and reliable for potential further developments into an application to be installed in containers. This dissertation concludes with remarks regarding future improvements and developments for the implemented work.
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Elhag, Anas. "Hyper-heuristics for grouping problems." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/34217/.
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Grouping problems are hard to solve combinatorial optimization problems which require partitioning of objects into a minimum number of subsets while another additional objective is simultaneously optimized. Considerable research e ort has recently been directed towards automated problem-independent reusable heuristic search methodologies such as hyper-heuristics, which operate on a space formed by a set of low level heuristics rather than solutions, directly. Hyper-heuristics are commonly split into two main categories: selection hyper-heuristics, which are the focus of the work presented in this thesis, and generation hyper-heuristics. Most of the recently proposed selection hyper-heuristics are iterative and make use of two key methods which are employed successively; heuristic selection and move acceptance. At each step, a new solution is produced after a selected heuristic is applied to the solution at hand and then the move acceptance method is used to decide whether the resultant solution replaces the current one or not. This thesis presents a novel generic single point-based selection hyper-heuristic search framework, referred to as grouping hyper-heuristic framework. The proposed framework deals with one solution at any given decision point during the search process and embeds axed set of reusable standard low level heuristics specifically designed for the grouping problems. The use of standard heuristics enables the re-usability of the whole framework across different grouping problem domains with less development effort. The proposed grouping hyper-heuristic framework is based on a bi-objective formulation of any given grouping problem. Inspired from multi-objective optimization, a set of high quality solutions is maintained during the search process, capturing the trade-of between the number of groups and the additional objective for the given grouping problem. Moreover, the grouping framework includes a special two-phased acceptance mechanism that use the traditional move acceptance method only to make a preliminary decision regarding whether to consider the new solution for acceptance or not. The performance of different selection hyper-heuristics combining different components, implemented based on the proposed framework is investigated on a range of sample grouping problem domains, including graph coloring, exam timetabling and data clustering domains. Additionally, the selection hyper-heuristics performing the best on each domain are compared to the previously proposed problem-specific algorithms from the scientific literature. The empirical results shows that the grouping hyper-heuristics built based on the proposed framework are not only sufficiently general, but also able to obtain high quality solutions, competitive to some previously proposed approaches. The selection hyper-heuristic employing the 'reinforcement learning' heuristic selection method and embedding the 'iteration limited threshold accepting' move acceptance method performs the best in the overall across those grouping problem domains.
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Sarkaria, Sarbjit Singh. "Neural networks for perceptual grouping." Thesis, Aston University, 1990. http://publications.aston.ac.uk/10653/.
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A number of researchers have investigated the application of neural networks to visual recognition, with much of the emphasis placed on exploiting the network's ability to generalise. However, despite the benefits of such an approach it is not at all obvious how networks can be developed which are capable of recognising objects subject to changes in rotation, translation and viewpoint. In this study, we suggest that a possible solution to this problem can be found by studying aspects of visual psychology and in particular, perceptual organisation. For example, it appears that grouping together lines based upon perceptually significant features can facilitate viewpoint independent recognition. The work presented here identifies simple grouping measures based on parallelism and connectivity and shows how it is possible to train multi-layer perceptrons (MLPs) to detect and determine the perceptual significance of any group presented. In this way, it is shown how MLPs which are trained via backpropagation to perform individual grouping tasks, can be brought together into a novel, large scale network capable of determining the perceptual significance of the whole input pattern. Finally the applicability of such significance values for recognition is investigated and results indicate that both the NILP and the Kohonen Feature Map can be trained to recognise simple shapes described in terms of perceptual significances. This study has also provided an opportunity to investigate aspects of the backpropagation algorithm, particularly the ability to generalise. In this study we report the results of various generalisation tests. In applying the backpropagation algorithm to certain problems, we found that there was a deficiency in performance with the standard learning algorithm. An improvement in performance could however, be obtained when suitable modifications were made to the algorithm. The modifications and consequent results are reported here.
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McCarter, Anna Kathryn. "Ability Grouping in Elementary Education." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2459.
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Ability grouping in education is a common practice used to differentiate instruction in order to meet the academic needs of students. The primary purpose for grouping students by ability is to increase their academic growth and achievement by providing instruction at the students’ current instructional level. However, there is much conflicting research regarding the impact of grouping students by ability and its link to student achievement. The purpose of this study was to determine if there is a statistically significant difference between school-wide student achievement in grades 3, 4, and 5 based on the type of grouping: ability grouped or not grouped by ability classroom settings. Data were collected from the Tennessee Department of Education website for the 2012-2013 academic school year as well as from individual school administrators regarding how students were grouped for instruction: grouped by ability or not grouped by ability. Independent samples t-tests were run to determine if there is a significant difference between students who received instruction in ability grouped setting and those that were not placed in an ability grouped classroom. The results of this study indicated that there is no difference in achievement scores based on the type of instructional setting (ability grouped or not grouped by ability) in reading and math in grades 3, 4, and 5.
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Tawil, Mohamad A. "Proposed Arabic grouping system and cross-map with the International Standard Organization ISO 9541 grouping system /." Online version of thesis, 1992. http://hdl.handle.net/1850/10939.
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Dandanelle, Alexander. "Efficient Frequency Grouping Algorithms for iDEN." Thesis, Linköping University, Department of Science and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2094.
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This Master’s Thesis deals with a special problem that may be of importance when planning a frequency hopping mobile communication network. In normal cases the Frequency Assignment Problem is solved, in order to plan the use of frequencies in a network. The special case discussed in this thesis occurs when the network operator requires that the frequencies must be arranged into groups. In this case the Frequency Assignment Problem must be solved with respect to the groups, i.e. a Group assignment Problem.
The thesis constitutes the final part of the Master of Science in Communication and Transport Systems Engineering education, at Linköping University, Campus Norrköping. The Group Arrangement Problem was presented by ComOpt, a company that has specialized in solving the Frequency Assignment Problem for network operators.
This thesis does not deal with solutions for the Frequency Assignment Problem, with respect to the groups. The main issue in the thesis is to construct a computer based algorithm that solves the Group Arrangement Problem, i.e. creating the groups. The goal is to construct an algorithm that creates groups which imply a better solution for the Frequency Assignment Problem than manually created groups.
Two algorithms are presented and tested on two cases. Their respective results for both cases are compared with the results from a manual grouping. The two computer based algorithms creates better groups than the manual grouping strategy, according to an artificial quality measure. As of spring 2003 a variant of one of the presented algorithms was implemented in ComOpt’s product for solving the Frequency Assignment Problem.
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Toriumi, Fujio, and Kenichiro Ishii. "EFFECT OF GROUPING ON CLASSROOM COMMUNITIES." INTELLIGENT MEDIA INTEGRATION NAGOYA UNIVERSITY / COE, 2006. http://hdl.handle.net/2237/10478.
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Oosten, Maarten. "A polyhedral approach to grouping problems." [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 1996. http://arno.unimaas.nl/show.cgi?fid=6706.
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Wang, Yong. "Clustering, grouping, and process over networks." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/Y_Wang_120707.pdf.
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Bock, Jacqueline Mary. "Perceptual grouping in visual word recognition." Thesis, University of York, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254606.
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Ahmad, Khalil. "Part grouping for efficient process planning." Thesis, Loughborough University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260262.
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Landry, Steven J. 1965. "Cognitive grouping in air traffic control." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/50550.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999.Includes bibliographical references (p. 83-87).
Subjects performing visual target tracking tasks have been shown to utilize perceptual organization. This organization has been shown to have both Gestalt features and goal-oriented features. Previous studies have attempted to use memory recall techniques to examine potential cognitive groupings in air traffic control tasks, with negative results. Analysis of eye movements has shown similar patterns of organization to the underlying visual tasks. Experiments were performed to evaluate whether recall or eye-tracking techniques can be used to extract perceptual groupings. Subjects' memory of scenario information is generally poor, except where significant manipulation of targets occurred. For this reason it is suggested that recall techniques may not be able to elicit subjects' cognitive groupings. Fixation data, however, indicates clustering consistent with Gestalt factors. Goal-oriented factors did not seem to affect grouping.
by Steven J. Landry.
S.M.
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Treimuth, Tambet. "Dynamic optimization of airspace sector grouping." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0013/document.
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Au cours de ces dernières décennies,au fur et à mesure de l’augmentation du trafic, l’espace aérien a été divisé en secteurs de plus en plus petits afin d’éviter la saturation de ces derniers. Ce principe de sectorisation présente une limite dans la mesure où l’on doit ménager un temps suffisant au contrôleur pour gérer son trafic et donc générer des secteurs dont la taille permet de satisfaire cette contrainte. De plus, le contrôleur ne connaît que le trafic lié à son secteur et lorsqu’un avion passe d’un secteur à un autre,il s’opère un dialogue entre les contrôleurs et les pilotes qui induit une charge de travail supplémentaire(coordination).Au cours d’une journée de trafic ordinaire,la charge de contrôle fluctue dans le temps en fonction des demandes de trafic entre les diverses paires origine-destination. Dans le système opérationnel actuel, le nombre de contrôleurs varie en fonction des fluctuations de trafic. La nuit par exemple, le nombre d’équipes de contrôle est réduit car il y a beaucoup moins de trafic.Les secteurs sont alors regroupés en groupe de trois à quatre avant attribution à une équipe de contrôleurs. Il est donc nécessaire d’optimiser la planification sur une journée du schéma de regroupement et de dégroupement des secteurs: resectorisation dynamique de l’espace aérien. Un des objectifs est de fournir des groupes de secteurs présentant un minimum de coordinations et équilibrés en terme de charge de contrôle afin que chaque équipe de contrôleurs travaille de la même façon. Les instants de commutation entre configurations de secteurs en fonction des fluctuations de trafic doivent être déterminés, et les distances entre configurations successives doivent être prises en compte afin d’éviter des changements brusques au sein d’un espace aérien donné. Le développement d’un algorithme efficace pour résoudre le problème dynamique résultant est d’autant plus important que le trafic aérien est amené évoluer de manière significative au cours des années qui viennentThe current airspace configuration is highly structured, fixed and is less responsive to changes causing the overall system to lack the flexibility, adaptability, and responsibility needed to handle the increasing air traffic demands in the near future. The work presented in this thesis aims at improving the flexibility and adaptability of today's airspace management in Europe in a pretactical context. We focus on the development of a method to support a process of automatic generation of a sequence of sector configurations composed of predefined sectors. Airspace configurations should be dynamically adjusted to provide maximum efficiency and flexibility in response to demand fluctuations. We dynamically build configurations by combining existing elementary sectors. In this step, any sector combination which forms controllable airspace blocks is eligible and may be used during the day of operation. In this work, we developed efficient methods to solve DAC problem. We formulated and study the sectorization problem from an algorithmic point of view. We proposed methods based on a mathematical modeling and heuristic optimization techniques. We also introduced here an approach to evaluate the workload inside sectors
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Cooper, Huw R. "Auditory grouping in cochlear implant listeners." Thesis, Aston University, 2008. http://publications.aston.ac.uk/12317/.
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This thesis describes a series of experiments investigating both sequential and concurrent auditory grouping in implant listeners. Some grouping cues used by normal-hearing listeners should also be available to implant listeners, while others (e.g. fundamental frequency) are unlikely to be useful. As poor spectral resolution may also limit implant listeners’ performance, the spread of excitation in the cochlea was assessed using Neural Response Telemetry (NRT) and the results were related to those of the perceptual tasks. Experiment 1 evaluated sequential segregation of alternating tone sequences; no effect of rate or evidence of perceptual ambiguity was found, suggesting that automatic stream segregation had not occurred. Experiment 2 was an electrode pitch-ranking task; some relationship was found between pitch-ranking judgements (especially confidence scores) and reported segregation. Experiment 3 used a temporal discrimination task; this also failed to provide evidence of automatic stream segregation, because no interaction was found between the effects of sequence length and electrode separation. Experiment 4 explored schema-based grouping using interleaved melody discrimination; listeners were not able to segregate targets and distractors based on pitch differences, unless accompanied by substantial level differences. Experiment 5 evaluated concurrent segregation in a task requiring the detection of level changes in individual components of a complex tone. Generally, large changes were needed and abrupt changes were no easier to detect than gradual ones. In experiment 6, NRT testing confirmed substantially overlapping simulation by intracochlear electrodes. Overall, little or no evidence of auditory grouping by implant listeners was found.
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Turina, Andreas. "A geometric framework for visual grouping." [S.l. : s.n.], 2002. http://e-collection.ethbib.ethz.ch/ecol-pool/diss/fulltext/eth14919.pdf.
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Utcke, Sven. "Error propagation in geometry-based grouping." [S.l. : s.n.], 2006.
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Ryan, Thomas Kennedy. "Grouping strategy in rhythmic perception: A test of the perceptual salience of Lerdahl and Jackendoff's grouping preference rules /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487942476406182.
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Condron, Dennis J. "Stratification, skill grouping, and learning to read in first grade." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1113411746.
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Thesis (Ph. D.)--Ohio State University, 2005.Document formatted into pages; contains x, 133 p.; also contains graphics. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 May 2.
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Desai, Sheila Elisabeth. "Pooling economic data : grouping individuals into households /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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August, Jonas. "From contour fragment grouping to shape decomposition." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0006/MQ29580.pdf.
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Khayat, Paul. "Attention and eye movements during contour grouping." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/72169.
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Landstad, Andreas Ståleson. "Enhanced Similarity Matching by Grouping of Features." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20114.
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In this report we introduce a classification system named Grouping of Features (GoF), together with a theoretical exploration of some of the important concepts in the Instant Based Learning(IBL)-field that are related to this system.A dataset's original features are by the GoF-system grouped together into abstract features. Each of these groups may capture inherent structures in one of the classes in the data. A genetic algorithm is used to extract a tree of such groups that can be used for measuring similarity between samples. As each class may have different inherent structures, different trees of groups are found for the different classes. To adjust the importance of one group in regards to the classifier, the concept of power average is used. A group's power-average may let either the smallest or the largest value of its group dominate, or take any value in-between. Tests show that the GoF-system outperforms kNN at many classification tasks.The system started as a research project by Verdande Technology, and a set of algorithms had been fully or partially implemented before the start of this thesis project. There existed no documentation however, so we have built an understanding of the fields on which the system relies, analyzed their properties, documented this understanding in explicit method descriptions, and tested, modified and extended the original system.During this project we found that scaling or weighting features as a data pre-processing step or during classification often is crucial for the performance of the classification-algorithm. Our hypothesis then was that by letting the weights vary between features and between groups of features, more complex structures could be captured. This would also make the classifier less dependent on how the features are originally scaled. We therefore implemented the Weighted Grouping of Features, an extension of the GoF-system.Notable results in this thesis include a 95.48 percent and 100.00 percent correctly classified non-scaled UCI Wine dataset using the GoF- and WGoF-system, respectively.
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August, Jonas. "From contour fragment grouping to shape decomposition." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26770.
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Bounding contours of physical objects are often fragmented by other occluding objects. This creates the need for perceptual grouping, or the association of those fragments corresponding to the same object. Perceptual grouping is currently a bottleneck to computer vision, since previous approaches either were heuristic, assumed the object belonged to restricted classes in order to exploit geometric invariants, or hypothesized boundary continuations. I introduce an alternative by invoking the principle that those fragments should be grouped whose fragmentation can be accounted for by a virtual occluder, and introduce the gap skeleton as a representation of this occluder. Properties of gap skeleton are proved, and an algorithm for computing it is given. Finally, a different perspective on gap skeleton is obtained in the domain of shape decomposition, where ligature emerges as the analog to gap skeleton. This leads to a new definition of a limb as a formal part, and suggests that both grouping and shape decomposition share a common basis.
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Havanur, Setu Gururaj. "The interaction between perceptual grouping and attention." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3289/.
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I investigated the interaction between perceptual grouping and attention, focusing specifically on distracter rejection. The novelty of the thesis lies in the study of different configural types and their effect on search across space and time. Grouping by configuration is likely to facilitate search by making distracter rejection easier. Grouping can be based on the regular locations of elements, the similarity of elements and whether the elements form a closed shape. The effects of grouping occurred under conditions in which the groups never contained the target, although detection was faster if the target fell internal to the group relative to when it fell outside the group. These results, together with those from neuropsychological studies reported here, are consistent with rapid suppression of irrelevant distractor groups. Primitive grouping, apparently based on clusters of similar proximal elements, took place even when attention was reduced in patients with chronic spatial biases in visual selection. However, neurological damage to attention-related brain regions did disrupt grouping effects dependent on element shape. Attention may, therefore, be more critical for some forms of grouping. Grouping interacts with attention to determine perceptual performance. This operates in a graded manner, determined by the type of grouping.
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Cham, Tat Jen. "Geometric representation and grouping of image curves." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627568.
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Tai, Anthony. "Perceptual grouping and knowledge-based vision systems." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/844407/.
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One of the goals in computer vision is to interpret scene objects and establish relationships between them. One of tire problems associated with this task is that the image to be interpreted and the objects to be recognised correspond to different levels of information. The image is, on the one hand, represented as a collection of pixels in which three-dimensional information is transformed into two-dimensional one under perspective projection dictated by the camera position as well as photometric parameters such as focal length etc. On the other hand, the object is represented as a collection of three-dimensional structures and relations between them. These rather different representations highlighted the need to construct an intermediate-level representation which can facilitate the accomplishment of the goal of establishing correspondence between image features and scene objects. The complexity of the interpretation task is further compounded by image imperfections caused by lighting, total reflectance, surface markings, accidental viewpoints and so on. The problems highlighted earlier motivated the development of a novel feature grouping framework which takes into account feature stability and the underlying noise. This work advanced the state of the art in perceptual group extraction as the existing techniques tend to be ad hoc. Built upon the framework that we have established we developed the computational representation of higher level features such as junctions, collinear line and parallel line groupings. The low level feature representation and extraction phases of the work were the necessary prerequisites for the extraction of intermediate representations using AI techniques. These representations serve as visual cues in our role-based system (RBS) to classify runways/taxiways in most of the DRA supplied imagery captured from unknown viewpoints. Complexity problems reported in previous work on RBS for low and intermediate level vision tasks are apparently overcome by identifying a set of prioritised feature cues, uncertainties are handled by hypothesis generation and hypothesis verification, and the method can be regarded as a constrained search through the space of candidate hypotheses.
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Justice, Matthew Adam. "Optimizing MongoDB-Hadoop Performance with Record Grouping." Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/244396.
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Computational cloud computing is more important than ever. Since time is literally money on cloud platforms, performance is the primary focus of researchers and programmers alike. Although distributed computing platforms today do a fine job of optimizing most types of workflows, there are some types, specifically those which are not computation-oriented, that are left out. After introducing important players in the world of computational cloud computing, this paper explores a possible performance enhancement for these types of workflows by reducing the overhead that platform designers assumed was acceptable. The enhancement is tested in two environments: an actual distributed computing platform and an environment that simulates that platform. Along the way it becomes clear that computational cloud computing is far from perfect and its use can often deliver surprising results. Regardless, the presented solution remains viable and is capable of increasing the performance of particular types of jobs by up to twenty percent.
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Eriksson, Therése, and Abdelnaeim Mohamed Mahmoud. "Waveform clustering - Grouping similar power system events." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-44147.
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Over the last decade, data has become a highly valuable resource. Electrical power grids deal with large quantities of data, and continuously collect this for analytical purposes. Anomalies that occur within this data is important to identify since they could cause nonoptimal performance within the substations, or in worse cases damage to the substations themselves. However, large datasets in the order of millions are hard or even impossible to gain a reasonable overview of the data manually. When collecting data from electrical power grids, predefined triggering criteria are often used to indicate that an event has occurred within the specific system. This makes it difficult to search for events that are unknown to the operator of the deployed acquisition system. Clustering, an unsupervised machine learning method, can be utilised for fault prediction within systems generating large amounts of multivariate time-series data without labels and can group data more efficiently and without the bias of a human operator. A large number of clustering techniques exist, as well as methods for extracting information from the data itself, and identification of these was of utmost importance. This thesis work presents a study of the methods involved in the creation of such a clustering system which is suitable for the specific type of data. The objective of the study was to identify methods that enables finding the underlying structures of the data and cluster the data based on these. The signals were split into multiple frequency sub-bands and from these features could be extracted and evaluated. Using suitable combinations of features the data was clustered with two different clustering algorithms, CLARA and CLARANS, and evaluated with established quality analysis methods. The results indicate that CLARA performed overall best on all the tested feature sets. The formed clusters hold valuable information such as indications of unknown events within the system, and if similar events are clustered together this can assist a human operator further to investigate the importance of the clusters themselves. A further conclusion from the results is that research into the use of more optimised clustering algorithms is necessary so that expansion into larger datasets can be considered.
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Akkapeddi, Raghu C. "Grouping annotating and filtering history information in VKB." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/227.
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History mechanisms available in hypertext systems allow users access to past interactions with the system and help users incorporate those interactions into the current context. The history information can be useful to both the system and the user. The Visual Knowledge Builder (VKB) creates spatial hypertexts - visual workspaces for collecting, organizing, and sharing. It is based on prior work on VIKI. VKB records all edit events and presents them in the form of a "navigable history" as end-users work within an information workspace. My thesis explores attaching user interpretations of history via the grouping and annotation of edit events. Annotations can take the form of a plain text statement or one or more attribute/value pairs attached to individual events or group of events in the list. Moreover, I explore the value of history event filtering, limiting the edits and groups presented to those that match user descriptions. My contribution in this thesis is the addition of mechanisms whereby users can cope with larger history records in VKB via the process of grouping, annotating and filtering history information.
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Mackey, Holly. "The Effects of Item Grouping on Test Reliability." TopSCHOLAR®, 2006. http://digitalcommons.wku.edu/theses/294.
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Optimal ordering of items on a multidimensional test has been the focus of several studies. In all but one study, previous research centered on measures of personality or opinion. The current study examines item grouping effects for a cognitive ability test. Two forms of a cognitive ability test containing four constructs (verbal ability, basic computation, number series, and spatial visualization) were prepared. Form A consisted of items grouped by construct, and Form B had items dispersed randomly throughout the test. The order of items within a construct remained the same for both forms. Tests were administered to 186 undergraduate psychology students. Coefficient alpha estimates of reliability on Form A were compared to coefficient alphas for the same constructs on Form B. Additionally, differences in mean scores across all four constructs and construct intercorrelations were compared by format. There were no significant differences in coefficient alphas and only one (basic computation) was in the hypothesized direction. There was only one significant construct intercorrelation pairing (basic computation vs. spatial visualization), and there were no significant differences in mean scores. Based on the lack of consistent findings, we found little support for a grouping effect for cognitive ability tests.
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Falkenauer, Emanuel. "The grouping genetic algorithms and their industrial applications." Doctoral thesis, Universite Libre de Bruxelles, 1994. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212706.
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Tsoumakos, Dimitrios. "Search, replication and grouping for unstructured P2P networks." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4077.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Computer Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Elagib, Tahani Y. "Marker-assisted heterotic grouping of Sudanese sorghum landraces /." Göttingen : Sierke, 2008. http://d-nb.info/987989642/04.
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Schaffalitzky, Frederik. "Grouping, matching and reconstruction in multiple view geometry." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249608.
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Neumüller, Mathias. "Grouping of semistructured data for efficient query processing." Thesis, University of Strathclyde, 2004. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21744.
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With the emergence of large-scale distributed computing applications semistructured data models have gained significant importance. Current practical semistructured data management systems can often not provide the performance required by practical applications. This work describes a model for the optimisation of semistructured data processing based on data groupings. Such groupings are of fundamental importance for efficient querying of semistructured data. The semistructured model does not imply the natural organisation of data that characterises rigidly structured representations. Instead, data groupings in the semistructured case must be derived from the data itself or its applications. This thesis presents a number of such possible data groupings and formalises them into a concept of domains. Different classes of domains are identified and the impact on different data sources is evaluated. A particular definition is then used to implement an efficient physical representation using an approach based on dictionary compression adapted from relational data management. Finally this approach is combined with a data grouping aimed at the efficient resolution of structural constraints.
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Chow, Hiu-mei, and 周曉薇. "The effect of perceptual grouping on selective attention." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50899946.
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Perceptual grouping plays an indispensable role on attention distribution. An example of this interaction is the impaired visual search performance when the target overlaps with a task-irrelevant salient distractor organized to a snake-like configuration by collinear bars, and when the collinear distractor is long enough (Jingling & Tseng, 2013). This phenomenon is puzzling because it is opposite to our understanding of attention capture which predicts search facilitation instead of impairment. As an attempt to fully understand the interaction between perceptual grouping and attention, the current research probed the possible neural stage of this collinear search impairment effect.
In Study 1, the distractor column of the search display was split into two eyes: one eye saw a distractor with varied length (= 1, 5, or 9 bars) while the other eye saw the rest of the distractor column. When both eyes were properly fused, observers saw a search display containing a 9-bar distractor. Observers were asked to identify the orientation of a target gap that could be overlapping or non-overlapping with the distractor. It was found that search impairment was dominated by monocular collinear distractor length.
In Study 2, a 9-bar distractor was shown to one eye of observers and strong flashing color patches were shown to the other eye (Continuous Flash Suppression) such that part of the distractor was suppressed from observers’ awareness. It was found that invisible collinear distractor parts enhanced search impairment, suggesting awareness of the distractor is not necessary for the effect.
Results from both studies converge to suggest that the effect of collinear grouping on attention is likely to be at early visual sites like V1 where monocular information but not awareness is processed. It highlights the need to incorporate perceptual grouping into current salience-based attention models.published_or_final_version
Psychology
Master
Master of Philosophy
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Blowers, Tracy. "Social Grouping Behaviors of Captive Female Hippopotamus Amphibius." Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3492.
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Levels of sociality vary depending on the costs and benefits associated with grouping behavior. Grouping species form either ephemeral aggregations due to resource availability, or structured groups based on familiarity of individuals. Because there are different costs and benefits associated with different types of groups, it is important to understand more about group structure before making predictions about specific behaviors. Female Hippopotamus amphibius are known to aggregate in the wild but the true nature of their grouping behavior is still not understood. My objective was to determine if captive female hippos form either ephemeral aggregations or social groups. Behavioral data, using continuous focal animal sampling and scan sampling, were collected on a group of nine captive female hippos housed at Disney's Animal Kingdom Theme Park. The behavioral data were used to analyze interactions between hippos, association patterns for kin and non-kin as well as familiarity, dominance hierarchy, and habitat preferences. My results support the hypothesis that hippos are forming social groups due to the attraction to particular individuals. There were more associations between kin than non-kin and also between individuals that have been together longer. Captive female hippos were also found to exhibit dominance patterns within the group. The results from this study may aid in the general understanding of hippopotamus behavior and aid in the captive management of hippos. Using my results as a starting point, research can begin looking at grouping patterns and its costs and benefits of sociality in wild hippopotamus populations.M.S.
Department of Biology
Sciences
Biology MS
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Lauprête, Geoffrey J. (Geoffrey Jean) 1972. "Some aspects of the optimal grouping of stocks." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/35480.
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Fixmer, Eric Norbert Charles. "Grouping of auditory and visual information in speech." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612553.
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Haber, Marian Wynne. "Ability Grouping in College Beginning Media Writing Classes." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc330684/.
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The problem with which this investigation is concerned is that students of unequal writing ability are frequently placed in the same beginning media writing classes in college journalism. It is difficult for a teacher to be effective when the ability of the students ranges from those who cannot write clear complete sentences to others whose work already appears in newspapers and magazines. The purpose of this study is to determine whether students who are ability grouped into slow—average and advanced groups do the same, better, or worse than heterogeneously grouped students. In the spring semester of 1987, students in Journalism 1345, Media Writing laboratory, at the University of Texas at Arlington, were given a pretest to determine how well they wrote a simple news story and a simple feature story. On the basis of that test, which was graded by three raters, the students were placed in two separate ability groups in three classes. The fourth class contained students with heterogeneous abilities who were not placed in groups. At the end of the semester a posttest was given in news and feature writing. A two-way analysis of variance was used to analyze the posttest scores of sixty-seven students. There was no significant difference in the posttest scores of students who were grouped homogeneously and those who were grouped heterogeneously. The difference in the scores of heterogeneously grouped advanced students and homogeneously grouped advanced students was not significantly different from the difference between the posttest scores of heterogeneously grouped slow-average students and homogeneously grouped slow-average students.
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Smith, G. Clark II. "Optimum Actuator Grouping in Feedforward Active Control Applications." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/36561.
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Previous work has demonstrated the benefit of grouping actuators to increase the controllability of an active control system, without increasing the number of control channels. By driving two or more secondary sources with the same control input, one is also able to reduce the hardware cost and complexity. In this work, a time domain cost function is developed for on-line actuator grouping and active structural acoustic control (ASAC) of a simply-supported beam excited with a broadband disturbance. Three PZT actuators are mounted on the beam structure to control the wavenumber components corresponding to five radiation angles. The propagation angles are selected to represent the total radiated sound power. The point force disturbance is bandlimited random noise which encompasses the first three modes of beam vibration. Actuators are considered grouped when their compensators are equal. Therefore, the cost function presented here incorporates an additional non-quadratic term which penalizes the controller for differences between the feedforward compensator coefficients. The backpropagation neural network algorithm provides the proper procedure to determine the minimum of this cost function.
The main disadvantage of using a stochastic gradient technique, while searching the prescribed control surface, is convergence to local minima. In this thesis, a resolution to this problem is suggested which incorporates using a variety of initial conditions. Two initialization conditions are considered: grouping actuators based upon weights determined by converging the filtered-x LMS algorithm and simultaneously grouping and controlling with the compensator weights initialized to small arbitrary numbers. Test cases of heavy and light grouping parameters were evaluated from both initial conditions. The computer simulations demonstrate the ability of this new form of the cost function to group actuators and control the error response with either initial condition. The heavy grouping cases achieved the same one channel control system from both initial conditions. The performance of the one channel solution was 1.5 dB lower than the performance of the ungrouped filtered-x LMS solution. The ability to select the different levels of grouping was demonstrated when the algorithm was initialized with the filtered-x LMS weights and run with light grouping parameters. For this case, the on-line algorithm grouped two actuators, but allowed the third actuator to exist independently. The performance of the two channel control system was only 0.6 dB less than the performance of the filtered-x LMS solution. In all grouping cases investigated, the convergence times of the grouping algorithm were within the same order as for the filtered-x LMS algorithm. The effect of uncorrelated error sensor noise on the actuator groupings is also briefly discussed.Master of Science
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Pecsok, Steven R. "Grouping and feeding policies for lactating dairy cows." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54259.
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Data from the University of New Hampshire were used to analyze dry matter intake and milk production in Holstein dairy cows. Equations predicting 4% FCM and dry matter intake were derived from this data using ordinary least squares. Days in milk, available nutrients, calving date, and previous period 4% FCM accounted for 90% of the variation in 4% FCM for heifers and 93% of the variation in 4% FCM for cows with previous lactations. Days in milk, acid detergent fiber, calving date, and dry matter intake from the previous 28 day period accounted for 71% of the variation in heifer dry matter intake and 79% of the variation in dry matter intake for the older cows. First period dry matter intake was predicted from first period 4% FCM, cow body weight, and acid detergent fiber of the ration. The lower R² for the first period dry matter intake (41% for heifers and 43% for cows with previous lactations) indicated that dry matter intake for a cow within a lactation was much more predictable than dry matter intake between different cows.
Rations were balanced for absolute amounts for simulated lactating cows using NRC requirements and 4% FCM and dry matter intake generated from the prediction equations. Relationships between 4% FCM and nutrient concentrations were determined for heifers and multiparous cows. These recommendations suggest maximum feeding of nutrients to groups producing at least 35 kg of 4% FCM daily. The effect of grouping and individual feeding on 4% FCM were analyzed. Independent variables included nutrient concentration, dry matter intake, groups, calving interval, variability of 305 day milk production within the herd, and level of feeding. Holding dry matter intake and nutrient concentrations constant, increasing the number of groups from one to two increased 4% FCM by 0%-3%, two groups to three groups by 0-2%, and three groups to four groups by 0-1%. Changing from one group to individual feeding increased 4% FCM by 2%-4% and two group to individual feeding increased 4% FCM by 0%-3%. The range of figures was influenced by herd production level, calving interval, and variability of within herd production. High variability of production favored additional groups, while high calving intervals favored individual feeding. To estimate expected change in profitability due to a change in grouping or feeding methods, multiply previous milk revenue by expected percentage change and subtract the increased cost of feeding.
Feeding less than the group average for nutrients was not found conducive for increasing profitability. In fact, production response to protein suggested that the low producing groups in multiple group feeding systems should be increased in protein slightly.
Individual feeding had the most potential for profitability, although group feeding compared favorably under some circumstances. If cows were grouped, a minimum of two groups was generally preferable. If the high producing group did not satisfy the needs of the high producing cows, or the drop in nutrients between groups was substantial, a three group system would appear more favorable.Ph. D.